Designs and methods of multi-function digital readout integrated circuits with an embedded programmable gate array

ABSTRACT

Embodiments disclosed herein relate to a ROIC with a plurality of unit cells coupled to a detector array having a plurality of detectors for collecting photoelectrons over a plurality of temporal instances. An individual unit cell is electrically coupled to an individual detector to have one-to-one correspondence and includes one or more storage elements coupled to one or more programmable logic control switches. The storage element(s) store signal charges representing the photoelectrons while the programmable logic control switch(es) direct the signal charges from the storage element(s) at an individual temporal instance. A configuration of signal charges in the plurality of unit cells is mathematically operated as a three-dimensional matrix having a plurality of elements, where the three dimensions correspond to the two spatial dimensions of an individual unit cell and the individual temporal instance, and an individual element has a value corresponding to the number of signal charges stored therein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent Application No. 62/662,449 entitled “Designs and Methods of Multi-Function Digital Readout Integrated Circuits with an Embedded Programmable Gate Array” and filed on Apr. 25, 2018, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present specification generally relates to multi-function digital readout integrated circuits (ROIC), and more specifically, to design and operation of multi-function ROICs that enable programmable controls in receiving, storing, and mathematically operating information extracted at or near the point of incidence of infrared radiation.

BACKGROUND

Traditional ROICs are typically designed to convert signal charges representing photoelectrons received from infrared radiation into voltage, and outputting the voltage signal possibly with a gain, or the digitized version of the voltage signal. In essence, a traditional ROIC is a charge-to-voltage converter, possibly followed by an analog-to-digital converter. Extraction of information is typically left to be conducted further downstream in the signal train, typically in the digital domain. This traditional approach encounters a range of practical operational challenges such as latency, weak noise performance, and output signal bandwidth requirements. The challenges become particularly acute for today's applications requiring low noise, desirable bandwidth, ultra large format, high frame rate, and dual-polarity ROICs and the multi-function sensors built on them.

SUMMARY

The present specification relates to a multi-function readout integrated circuit (ROIC) with an embedded programmable gate array. In one embodiment, a ROIC is coupled to a detector array having a plurality of detectors for collecting photoelectrons over a plurality of temporal instances. The ROIC includes a plurality of unit cells arranged in two spatial dimensions. An individual unit cell of the plurality of unit cells is electrically coupled to an individual detector of the plurality of detectors to have one-to-one correspondence. An individual unit cell includes one or more storage elements and one or more programmable logic control switches coupled to the one or more storage elements. The one or more storage elements store signal charges representing the photoelectrons collected by the detector array at an individual temporal instance of the plurality of temporal instances. The one or more programmable logic control switches direct the signal charges towards or away from the one or more storage elements at the individual temporal instance. A configuration of signal charges in the plurality of unit cells is mathematically represented and operated as a matrix in three dimensions having a plurality of elements, where the three dimensions correspond to the two spatial dimensions and the individual temporal instance. An individual element of the matrix has a value corresponding to the number of signal charges stored in the individual unit cell at the individual temporal instance.

In another embodiment, an infrared sensor assembly includes a detector array and a ROIC coupled to the detector array. The detector array has a plurality of detectors for collecting photoelectrons over a plurality of temporal instances. The ROIC is coupled to the detector array and includes a plurality of unit cells arranged in two spatial dimensions. An individual unit cell of the plurality of unit cells is electrically coupled to an individual detector of the plurality of detectors to have one-to-one correspondence. An individual unit cell includes one or more storage elements and one or more programmable logic control switches coupled to the one or more storage elements. The one or more storage elements store signal charges representing the photoelectrons collected by the detector array at an individual temporal instance of the plurality of temporal instances. The one or more programmable logic control switches direct the signal charges towards or away from the one or more storage elements at the individual temporal instance. A configuration of signal charges in the plurality of unit cells is mathematically represented and operated as a matrix in three dimensions having a plurality of elements, where the three dimensions correspond to the two spatial dimensions and the individual temporal instance. An individual element of the matrix has a value corresponding to the number of signal charges stored in the individual unit cell at the individual temporal instance of the plurality of temporal instances.

These and additional features provided by the embodiments described herein will be more fully understood in view of the following detailed description, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

FIG. 1 depicts a schematic illustration of a side view of an infrared sensor assembly having a readout integrated circuit (ROIC) coupled to a detector array, according to one or more embodiments shown and described herein;

FIG. 2A depicts a schematic illustration of an example circuit topology used in the ROIC of an infrared sensor assembly, according to one or more embodiments shown and described herein;

FIG. 2B depicts an example circuit module used in the example circuit topology of FIG. 2A, according to one or more embodiments shown and described herein;

FIG. 3A depicts an example circuit module for implementing a temporal shifting of signal charges stored within the ROIC at different temporal instances, according to one or more embodiments shown and described herein;

FIG. 3B depicts a flow diagram representing a function of the example circuit module of FIG. 3A, according to one or more embodiments shown and described herein;

FIG. 4A depicts an example circuit module for determining a summation of signal charges stored within the ROIC at different temporal instances, according to one or more embodiments shown and described herein;

FIG. 4B depicts a flow diagram representing a function of the example circuit module of FIG. 4A, according to one or more embodiments shown and described herein;

FIG. 5A depicts an example circuit module for determining a maximum value of signal charges stored within the ROIC at different temporal instances, according to one or more embodiments shown and described herein;

FIG. 5B depicts a flow diagram representing a function of the example circuit module of FIG. 5A, according to one or more embodiments shown and described herein;

FIG. 6A depicts an example circuit module for determining an increasing or decreasing trend of signal charges stored within the ROIC at different temporal instances, according to one or more embodiments shown and described herein;

FIG. 6B depicts a flow diagram representing a function of the example circuit module of FIG. 6A, according to one or more embodiments shown and described herein;

FIG. 7A depicts an example circuit module for determining a difference of signal charges stored within the ROIC at different temporal instances, according to one or more embodiments shown and described herein;

FIG. 7B depicts a flow diagram representing a function of the example circuit module of FIG. 7A, according to one or more embodiments shown and described herein;

FIG. 8A depicts an example circuit module for determining a comparison of signal charges stored within the ROIC to a threshold value, according to one or more embodiments shown and described herein;

FIG. 8B depicts a flow diagram representing a function of the example circuit module of FIG. 8A, according to one or more embodiments shown and described herein;

FIG. 9A depicts an example circuit module for implementing a spatial shifting of signal charges stored across different unit cells within the ROIC, according to one or more embodiments shown and described herein;

FIG. 9B depicts a flow diagram representing a function of the example circuit module of FIG. 9A, according to one or more embodiments shown and described herein;

FIG. 10A depicts an example circuit module for determining a summation of signal charges stored across different unit cells within the ROIC, according to one or more embodiments shown and described herein;

FIG. 10B depicts a flow diagram representing a function of the example circuit module of FIG. 9A, according to one or more embodiments shown and described herein;

FIG. 11A depicts an example circuit module for determining a maximum value of signal charges stored across different unit cells within the ROIC, according to one or more embodiments shown and described herein;

FIG. 11B depicts a flow diagram representing a function of the example circuit module of FIG. 10A, according to one or more embodiments shown and described herein;

FIG. 12A depicts an example circuit module for determining an increasing or decreasing trend of stored signal charges across different unit cells within the ROIC, according to one or more embodiments shown and described herein;

FIG. 12B depicts a flow diagram representing a function of the example circuit module of FIG. 11A, according to one or more embodiments shown and described herein;

FIG. 13A depicts a first example circuit module for determining a difference of signal charges stored across different unit cells within the ROIC, according to one or more embodiments shown and described herein;

FIG. 13B depicts a second example circuit module for determining a difference of signal charges stored across different unit cells within the ROIC, according to one or more embodiments shown and described herein; and

FIG. 13C depicts a flow diagram representing a function of the example circuit modules of FIGS. 13A-13B, according to one or more embodiments shown and described herein.

DETAILED DESCRIPTION

Embodiments described herein are directed to multi-function ROICs with an embedded programmable gate array. The individual unit cells of the ROICs described herein have different combinations of one or more circuit modules for receiving, storing and mathematically operating signal charges received from the individual detectors of a detector array over a period of time. Circuit topologies having different combinations of the one or more circuit modules are designed to function as an embedded programmable gate array within the ROIC. Accordingly, the signal charges within the individual unit cells as well as across different subsets of individual unit cells within the ROIC can be controlled for extraction of information in the ROIC itself and subsequent production of infrared images. The extraction of information-enriched data at or near the point of incidence of the infrared radiation and subsequent processing of the information-enriched data in the analog domain enables the production of infrared images with the least latency, minimal noise, while consuming the least amount of bandwidth and energy.

Referring to FIG. 1, a schematic illustration of a side view of an infrared sensor assembly 100 is depicted. The infrared sensor assembly 100 has a detector array 110 coupled to a readout integrated circuit (ROIC) 160 through a bonding bump 150 _(i). The detector array 110 includes a plurality of detectors 115 _(i) for collecting photoelectrons over a plurality of temporal instances T_(i). While the detector array 110 depicted in FIG. 1 is an infrared focal plane array and the individual detector 115 _(i) represents an individual pixel of a plurality of pixels of the focal plane array, the embodiments described herein are not limited as such. The non-limiting example individual detector 115 _(i) of the detector array 110 shown in FIG. 1 includes a transparent substrate 122 disposed between two anti-reflective layers 124 and 124′, a frontside common electrical contact 120, a pyramid-shaped absorber layer 130 and a backside electrical contact 140. It should be understood that embodiments are not limited to the detector 115 _(i) shown in FIG. 1, and the detector array 110 may take on other configurations. While the detector array 110 includes a plurality of detectors 115 _(i), only one detector 115 _(i) is illustrated in FIG. 1 for ease of illustration.

The transparent substrate 122 comprises a material that is transparent to radiation in the desired wavelength, such as wavelengths in the infrared or near-infrared spectrum. The transparent substrate 122, which may be made of silicon, for example, provides a window or an entry point for radiation (illustrated as arrows 170) into the detector array 110. Optional anti-reflective layers 124 and 124′ may be applied to the transparent substrate 122 to increase the infrared radiation entering the detector array 110.

The absorber layer 130 is coupled to the frontside common electrical contact 120 at a first end and the backside electrical contact 140 at a second end opposite to the first end. In one embodiment, the absorber layer 130 is bonded to the transparent substrate 122 via an adhesive bonding layer 116 such as, but not limited to, an epoxy adhesive. The backside electrical contact 140 is connected to a surface 132 of the absorber layer 130.

The ROIC 160 includes a ROIC substrate (of M rows and N columns) divided into a plurality of unit cells 165 _(i) arranged in two spatial dimensions (say, X_(i) and Y_(i) on the plane of the ROIC 160). While the ROIC 160 includes the plurality of unit cells 165 _(i), only one unit cell 165 _(i) is illustrated in FIG. 1 for ease of illustration. The individual unit cell 165 _(i) is electrically coupled to an individual detector 115 _(i) through the bonding bump 150 _(i) and an electrical contact 162 of the ROIC 160 to form a one-to-one correspondence.

In operation, infrared radiation (illustrated by arrows 170) is transmitted through the transparent substrate 122 and the anti-reflective layers 124 and 124′ into the absorber layer 130. The absorber layer 130 converts the incident infrared radiation into photoelectrons that are transmitted as signal charges through the bonding bump 150 _(i) and the electrical contact 162 into the individual unit cell 165 _(i).

The individual unit cells 165 _(i) have different combinations of one or more circuit modules 165 _(ai) for receiving, storing and mathematically operating the signal charges received from the individual detectors 115 _(i). The individual circuit module 165 _(ai) includes one or more storage elements C_(i) for storing signal charges representing the photoelectrons collected by the corresponding detector 115 _(i) at the individual temporal instance T_(i). In some embodiments, the storage element C_(i) for storing signal charges may be a capacitor, though in other embodiments, any electrical or electronic component capable of storing charges may be used. The one or more storage elements C_(i) are coupled to one or more programmable logic control switches S_(i) for directing the signal charges towards or away from the one or more storage elements C_(i) at the individual temporal instance T_(i).

A configuration of signal charges stored in the plurality of unit cells 165 _(i) at the individual temporal instance T_(i) can be mathematically represented by a three-dimensional matrix P_(Ti) having a plurality of elements q_(i), where the three dimensions correspond to the two spatial dimensions X_(i), Y_(i) of the individual unit cell 165 _(i) (row number and column number of the unit cells 165 _(i)) and the individual temporal instance T_(i). The number of signal charges stored in the unit cell 165 _(i) having dimensions X_(i), Y_(i) at the individual temporal instance T_(i) can thus be represented by a unique value as a function of X_(i), Y_(i) and T_(i) and forms the individual element q_(i) of the three-dimensional matrix P_(Ti). Accordingly, the three-dimensional matrix P_(Ti) having a plurality of elements q_(i) can be mathematically operated to extract information from the signal charges. Any mathematically allowable operation of the three-dimensional matrix P_(Ti), regardless of the number of operands, can perceivably be performed to achieve a desired outcome by programmable logic control switches purposely designed in and controlled by the programmable logic gates, to achieve such desired outcome, preferably in the analog domain to achieve the intended benefits.

Circuit topologies having different combinations of one or more circuit modules 165 _(ai) can function as embedded programmable gate arrays within the ROIC 160. FIG. 2A depicts a schematic illustration of an example circuit topology using the exemplary circuit module 165 _(ai) shown in FIG. 2B. The exemplary circuit module 165 _(ai) includes a storage element C_(x) electrically connected to an individual programmable logic control switch G_(x1) at one end and to another individual programmable logic control switch G_(x2) at the opposite end. The individual programmable logic control switch G_(x2) is electrically connected at the other end to a controllable voltage source V_(x) (bias control). Accordingly, when the individual programmable logic control switch G_(x1) is closed at an individual temporal instance T_(i), signal charges are directed towards the storage element C_(x) in series with the individual programmable logic control switch G_(x1). The individual programmable logic control switch G_(x2) is used to connect to different bias V_(x) at logically-controlled timing.

Any number of circuit modules 165 _(ai) such as, but not limited to, the one shown in FIG. 2B and the ones shown in FIGS. 3A, 4A, 5A, 6A, 7A, and 8A can be combined in series or parallel within the individual unit cell 165 _(i). The resultant combination of physical circuit modules 165 _(ai) in the individual unit cell 165 _(i), together with any necessary circuitry usually residing in the periphery of the unit cells 165 _(i), forms an embedded programmable gate array. The embedded programmable gate array can be represented mathematically as the three-dimensional matrix P_(Ti) and operated in the signal domain in a sequence of matrix operations to control the input and manipulate the output of signal charges stored in the multiple storage elements C_(x) of the individual unit cells 165 _(i) as is shown in FIG. 2A. Bias control and/or sequential operation of a number of programmable logic control switches can be used to support dual polarity of the storage elements C_(x) to direct the flow of signal charges towards or away from the storage elements C_(x).

In the example circuit topology of the individual unit cell 165 _(i) shown in FIG. 2A, signal charges can pass through a set of the programmable logic control switches G={G₀₀, G₁₁, G₁₂, G₂₁, G₂₂, G₃₁, G₃₂, G₄₁, G₄₂, G₅₁, G₅₂, G₆₁, G₆₂, G₇₇, . . . } or a subset thereof before leaving the individual unit cell 165 _(i). The signal charges are directed towards or away from the one or more storage elements C_(x) in series with the individual programmable logic control switches G_(x1), depending on whether the individual programmable logic control switches G_(x1) form a closed switch or an open switch respectively. If the programmable logic control switch G₀₀ is closed, the signal charges enter the individual unit cell 165 _(i). On the other hand, if the programmable logic control switch G₀₀ is open, the signal charges cannot enter the individual unit cell 165 _(i). The examples described below demonstrate how signal charges can be directed to move through the example circuit topology of the individual unit cell 165 _(i) shown in FIG. 2A.

In a first non-limiting example, the signal charges may be subsequently stored in the storage element C₁ if the programmable logic control switch G₁₁ is closed, G₁₂ closed to a proper bias V₁, and the programmable logic control switches G₂₁, G₅₁ and G₆₁ are open and will remain stored in C₁. The signal charges stored in the storage element C₁ may subsequently be directed towards the storage element C₂ by keeping the programmable logic control switches G₅₁, and G₆₁ open and closing the programmable logic control switches G₁₁ and G₂₁ with G₂₂ closed to a proper bias V₂. As an alternative, the signal charges stored in the storage element C₁ may be directed towards the storage element C₃ by keeping the programmable logic control switches G₂₁, G₅₂ and G₆₁ open and closing the programmable logic control switches G₁₁, G₃₁ and G₅₁, with G₃₂ closed to a proper bias V₃. As another alternative, the signal charges stored in the storage element C₁ may be directed towards the storage element C₄ by keeping the programmable logic control switches G₂₁, G₅₁ and G₆₂ open and closing the programmable logic control switches G₁₁, G₄₁ and G₆₁ with G₄₂ closed to a proper bias V₄. Finally, the signal charges stored in the storage element C₁ may be directed towards an adjacent unit cell 165 _(i) or read out by keeping the programmable logic control switches G₂₁, G₃₁ and G₄₁ open and closing the programmable logic control switches G₁₁, G₇₇, and either both programmable logic control switches G₅₁, G₅₂ or both programmable logic control switches. G₆₁, G₆₂, while keeping G₁₂ closed to a proper bias V₁.

In a second non-limiting example, the signal charges may be subsequently stored in the storage element C₂ if the programmable logic control switch G₂₁ is closed, G₂₂ closed to a proper bias V₂, and the programmable logic control switches G₁₁, G₅₁ and G₆₁ are open and will remain stored in C₂. The signal charges stored in the storage element C₂ may subsequently be directed towards the storage element C₁ by keeping the programmable logic control switches G₅₁, and G₆₁ open and closing the programmable logic control switches G₁₁ and G₂₁ with G₁₂ closed to a proper bias V₁. As an alternative, the signal charges stored in the storage element C₂ may be directed towards the storage element C₃ by keeping the programmable logic control switches G₁₁, G₅₂ and G₆₁ open and closing the programmable logic control switches G₂₁, G₃₁ and G₅₁ with G₃₂ closed to a proper bias V₃. As another alternative, the signal charges stored in the storage element C₂ may be directed towards the storage element C₄ by keeping the programmable logic control switches G₁₁, G₅₁ and G₆₂ open and closing the programmable logic control switches G₂₁, G₄₁ and G₆₁ with G₄₂ closed to a proper bias V₄. Finally, the signal charges stored in the storage element C₂ may be directed towards an adjacent unit cell 165 _(i) or read out by keeping the programmable logic control switches G₁₁, G₃₁ and G₄₁ open and closing the programmable logic control switches G₂₁, G₇₇, and either both programmable logic control switches G₅₁, G₅₂ or both programmable logic control switches. G₆₁, G₆₂, while keeping G₂₂ closed to a proper bias V₂.

In a third non-limiting example, the signal charges may be subsequently stored in the storage element C₃ if the programmable logic control switches G₁₁, G₂₁, G₅₂ and G₆₁ are open and the programmable logic control switches G₅₁ and G₃₁ are closed with G₃₂ closed to a proper bias V₃, and will remain in C₃. The signal charges stored in the storage element C₃ may be directed towards the storage element C₁ by keeping the programmable logic control switches G₅₂, G₂₁ and G₆₁ open and closing the programmable logic control switches G₁₁, G₃₁ and G₅₁ with G₃₂ closed to a proper bias V₃. As an alternative, the signal charges stored in the storage element C₃ may be directed towards the storage element C₂ by keeping the programmable logic control switches G₅₂, G₁₁ and G₆₁ open and closing the programmable logic control switches G₂₁, G₃₁ and G₅₁ with G₃₂ closed to a proper bias V₃. As another alternative, the signal charges stored in the storage element C₃ may be directed towards the storage element C₄ by keeping the programmable logic control switches G₁₁, G₂₁, G₅₂ and G₆₂ open and closing the programmable logic control switches G₃₁, G₄₁, G₅₁ and G₆₁ with G₃₂ closed to a proper bias V₃ and with G₄₂ closed to a proper bias V₄. Finally, the signal charges stored in the storage element C₃ may be directed towards an adjacent unit cell 165 _(i) or read out by keeping the programmable logic control switches G₆₂ and G₅₁ open and closing the programmable logic control switches G₅₂ and G₇₇ with G₃₂ closed to a proper bias V₃.

In a fourth non-limiting example, the signal charges may be subsequently stored in the storage element C₄ if the programmable logic control switches G₁₁, G₂₁, G₆₂ and G₅₁ are open and the programmable logic control switches G₆₁ and G₄₁ are closed with G₄₂ closed to a proper bias V₄, and will remain in C₄. The signal charges stored in the storage element C₄ may be directed towards the storage element C₁ by keeping the programmable logic control switches G₆₂, G₂₁ and G₅₁ open and closing the programmable logic control switches G₁₁, G₄₁ and G₆₁ with G₄₂ closed to a proper bias V₄. As an alternative, the signal charges stored in the storage element C₄ may be directed towards the storage element C₂ by keeping the programmable logic control switches G₆₂, G₁₁, and G₅₁ open and closing the programmable logic control switches G₂₁, G₄₁ and G₆₁ with G₄₂ closed to a proper bias V₄. As another alternative, the signal charges stored in the storage element C₄ may be directed towards the storage element C₃ by keeping the programmable logic control switches G₁₁, G₂₁, G₅₂ and G₆₂ open and closing the programmable logic control switches G₃₁, G₄₁, G₅₁ and G₆₁ with G₄₂ closed to a proper bias V₄ and with G₃₂ closed to a proper bias V₃. Finally, the signal charges stored in the storage element C₄ may subsequently be directed towards an adjacent unit cell 165 _(i) or read out by keeping the programmable logic control switches G₅₂ and G₆₁ open and closing the programmable logic control switches G₆₂ and G₇₇ with G₄₂ closed to a proper bias V₄.

The examples above demonstrate how the signal charges can be stored and directed to move through the example circuit topology of the individual unit cell 165 _(i) of FIG. 2A. Accordingly, a circuit topology comprising at least two storage elements C₁ and C₂ can enable signal charges received at a first temporal instance T₁ to be stored in the first storage element C₁ during a second temporal instance T₂ while signal charges received at the second temporal instance T₂ are directed to move or stored in a second storage element C₂. The signal charges stored in the first storage element C₁ may become a first operand and the signal charges present in the second storage element C₂ may become a second operand that can then be mathematically operated on to form a third operand.

Similarly, a circuit topology comprising at least three storage elements—a first storage element C₁, a second storage element C₂, and a third storage element C₃—can enable signal charges received at a first temporal instance T₁ to be stored in the first storage element C₁ during a second temporal instance T₂ while signal charges received at the second temporal instance T₂ are directed to move or stored in a second storage element C₂. The signal charges stored in the first storage element C₁ become a first operand and the signal charges present in the second storage element C₂ become a second operand that can then be mathematically operated on to form a third operand stored in the third storage element C₃.

Alternatively, a circuit topology comprising at least four storage elements—a first storage element C₁, a second storage element C₂, a third storage element C₃ and a fourth storage element C₄—can enable signal charges received at a first temporal instance T₁ to be stored in the first storage element C₁ during a second temporal instance T₂ while signal charges received at the second temporal instance T₂ are directed to move or stored in a second storage element C₂. The signal charges stored in the first storage element C₁ become a first operand and the signal charges present in the second storage element C₂ become a second operand that can then be mathematically operated on to form a third operand stored in the first storage element C₁, the second storage element C₂ or the fourth storage element C₄ at a third temporal instance T₃, during which a third set of signal charges are received and stored in the third storage element C₃. The signal charges stored in the third storage element C₃ become a fourth operand. The third operand and the fourth operand can then be mathematically operated on to form a fifth operand.

In some embodiments, the signal charges stored at multiple temporal instances T_(i) can be temporarily stored and later operated on in a range of mathematical operations. The signal charges stored temporarily over a sequence of temporal instances T_(i) may be rearranged in numerous ways to extract information from the incident infrared radiation. The mathematical operations may include, without limitation, determining whether a signal charge meets a threshold value, a summation of signal charges, determining a maximum value of signal charges, determining a difference of signal charges or determining an increasing or decreasing trend.

The addition of the signal charges stored in the first storage element C₁ and the second storage element C₂ of the individual unit cell 165 _(i) may be accomplished by electrically connecting in parallel the storage elements C₁ and C₂, which enables voltage equalization and summation of the signal charges stored therein. The resultant voltage is the weighted average of signal charges stored in the storage elements C₁ and C₂ and can be analyzed, for example by measuring the gain of an amplifier electrically connected directly to the individual unit cell 165 _(i), to find the summation of the signal charges.

Determining a difference of signal charges stored in the first storage element C₁ and the second storage element C₂ of the individual unit cell 165 _(i) may be accomplished by reversing a polarity of the first storage element C₁ or the second storage element C₂ after the first storage element C₁ stores the signal charges directed thereto and the second storage element C₂ stores the signal charges directed thereto and then electrically connecting the first storage element C₁ in parallel to the second storage element C₂. In some embodiments such as shown in FIG. 2A, the reversal of polarity can be accomplished by proper bias control at the controllable voltage source V₁ and V₂ depending on whether the polarity of the first storage element C₁ or the polarity of the second storage element C₂ is reversed. In other embodiments, the reversal of polarity can be accomplished by sequential operation of a number of programmable logic control switches, as described below.

The above two mathematical operations combined allow a direct output of the “Luminance” and “Chrominance” in a two-color sensor operation and achieve histogram equalization if an additional gain amplifier is employed, circumventing many steps in external processing.

The capability to perform one or more mathematical operations is not limited to two operands and can extend to multiple operands derived from one or more mathematical operations or from signal charges received and stored at different temporal instances T_(i) within the individual unit cell 165 _(i). A time series analysis can thus be performed using the signal charges received over a plurality of temporal instances T_(i), both for the individual unit cell 165 _(i) as well as for the plurality of unit cells 165 _(i) forming the ROIC 160.

While the examples above demonstrate only a few ways in which the signal charges stored in one or more storage elements C_(x) can be controlled using one or more programmable logic control switches G_(x1), G_(x2), various other ways of controlling the stored signal charges within the individual unit cell 165 _(i) as well as across different subsets of individual unit cells 165 _(i) within the ROIC 160 are contemplated to be included within the scope and content of the disclosure. The embedded programmable gate array formed by the resultant combination of individual circuit modules 165 _(ai) within the individual unit cell 165 _(i) can be programmed through the temporal operation of a set of the programmable logic control switches G={G₀₀, G₁₁, G₁₂, G₂₁, G₂₂, G₃₁, G₃₂, G₄₁, G₄₂, G₅₁, G₅₂, G₆₁, G₆₂, G₇₇, . . . } or a subset thereof within the individual unit cell 165 _(i) as well as different subsets of individual unit cells 165 _(i)—representable by a three-dimensional matrix P_(i) described above—within the ROIC 160. The storage and control of signal charges in the plurality of unit cells 165 _(i) over the plurality of temporal instances T_(i) thus advantageously enables moving frames of infrared images to be captured over a desired time of exposure to infrared radiation.

Various example embodiments of circuit modules 165 _(ai) are now discussed below to demonstrate the possibilities for mathematically operating on the signal charges flowing into the individual unit cell 165 _(i) of the ROIC 160.

FIG. 3A depicts an example circuit module 300 (implementable as the circuit module 165 _(ai)) for implementing a temporal shifting of signal charges stored within the ROIC 160 at different temporal instances T_(i). FIG. 3B depicts a flow diagram representing a function of the example circuit module 300 of FIG. 3A. The example circuit module 300 includes a first storage element C₁ and a second storage element C₂ electrically connected through a programmable logic control switch S. The programmable logic control switch S can be operated to direct signal charges from the first storage element C₁ to the second storage element C₂. Thus signal charges received at a first temporal instance (t−1) can be stored in the first storage element C₁ and subsequently copied into the second storage element C₂ during a second temporal instance (t). The temporal instances (t−1) and (t) may be successive temporal instances. Accordingly, the signal charges stored in the first storage element C₁ at the first temporal instance (t−1) from the detector 115 _(i) is Q(t−1), shown in box 300 a. The signal charges directed into the second storage element C₂ at the second temporal instance (t) is Q(t), shown in box 300 b. The signal charges Q(t−1) and Q(t) can be then read out, one at a time, from the individual unit cell 165 _(i) to verify that Q(t−1)=Q(t).

FIG. 4A depicts an example circuit module 400 (implementable as the circuit module 165 _(ai)) for determining a summation 450 of signal charges stored within the ROIC 160 over different temporal instances T_(i). FIG. 4B depicts a flow diagram representing a function of the example circuit module 400 of FIG. 4A. The example circuit module 400 includes three storage elements—a first storage element C₁, a second storage element C₂ and a third storage element C₃ situated in parallel. It should be understood that more than three storage elements may be provided in other embodiments of the example circuit module 400. A programmable logic control switch S is connected to the programmable logic control switches S₁, S₂ and S₃ for directing signal charges to the first storage element C₁ at a temporal instance (t−2), the second storage element C₂ at a temporal instance (t−1) and the third storage element C₃ at a temporal instance (t) respectively. The temporal instances (t−2), (t−1) and (t) may be successive temporal instances. Accordingly, the signal charges stored in the first storage element C₁ at the first temporal instance (t−2) from the detector 115 _(i) is Q(t−2), shown in box 400 a. The signal charges stored in the second storage element C₂ at the second temporal instance (t−1) from the detector 115 _(i) is Q(t−1), shown in box 400 b. The signal charges stored in the third storage element C₃ at the third temporal instance (t) from the detector 115 _(i) is Q(t), shown in box 400 c. When the first storage element C₁, the second storage element C₂ and the third storage element C₃ are electrically connected in parallel, the resultant voltage is the weighted average voltage representing the summation 450 of the signal charges Q(t−2), Q(t−1), and Q(t), SUM(Q)=[Q(t−2)+Q(t−1)+Q(t)].

FIG. 5A depicts an example circuit module 500 (implementable as the circuit module 165 _(ai)) for determining a maximum value 550 of signal charges stored within the ROIC 160 over different temporal instances T_(i). FIG. 5B depicts a flow diagram representing a function of the example circuit module 500 of FIG. 5A. The example circuit module 500 includes three storage elements—a first storage element C₁, a second storage element C₂ and a third storage element C₃ situated in parallel. It should be understood that more or fewer storage elements may be provided in the example circuit module 500. A first programmable logic control switch S₁ is switchably connected to the first storage element C₁ storing signal charges at a temporal instance (t−2). The voltage developed across the first storage element C₁ due to signal charges is applied to a metal-oxide-semiconductor-field-effect-transistor (MOSFET) amplifier Q₁, which is configured as a source-follower amplifier in conjunction with the output bias current generator BCG. A second programmable logic control switch S₂ is switchably connected to the second storage element C₂ storing signal charges at a temporal instance (t−1) and the voltage is applied to a MOSFET amplifier Q₂. A third programmable logic control switch S₃ is switchably connected to the third storage element C₃ storing signal charges at a temporal instance (t) and the voltage is applied to a MOSFET amplifier Q₃. The temporal instances (t−2), (t−1) and (t) may be successive temporal instances. Accordingly, the signal charges stored in the first storage element C₁ at the first temporal instance (t−2) from the detector 115 _(i) is Q(t−2), shown in box 500 a. The signal charges stored in the second storage element C₂ at the second temporal instance (t−1) from the detector 115 _(i) is Q(t−1), shown in box 500 b. The signal charges stored in the third storage element C₃ at the third temporal instance (t) from the detector 115 _(i) is Q(t), shown in box 500 c. Each output of source-follower amplifiers Q₁, Q₂ and Q₃ is applied to a common bias current connection through the bias current generator BCG so that only the amplifier with the largest input voltage will conduct current and thereby indicate the output voltage, which represents the maximum value 550 of the signal charges stored in the storage elements C₁, C₂ and C₃, MAX(Q)=maximum value {Q(t−2), Q(t−1), Q(t)}.

As a non-limiting example, a combination of the example circuit module 400 and the example circuit module 500 can be used to determine a maximum value of either the present value of signal charges residing in the third storage element C₃ or the average of past values of signal charges in the second storage element C₂ and the first storage element C₁ stored at the successive temporal instances (t−1) and (t−2) respectively. The first storage element C₁ and the second storage element C₂ storing signal charges at the successive temporal instances (t−2) and (t−1) respectively are first electrically connected in parallel prior to reading the combined source-follower amplifier output.

FIG. 6A depicts an example circuit module 600 (implementable as the circuit module 165 _(ai)) for determining an increasing or decreasing trend 650 of signal charges stored within the ROIC 160 over different temporal instances T_(i). FIG. 6B depicts a flow diagram representing a function of the example circuit module 600 of FIG. 6A. The example circuit module 600 includes two storage elements—a first storage element C₁ and a second storage element C₂ situated in parallel. A first programmable logic control switch S₁ is electrically connected to the first storage element C₁ storing signal charges at a temporal instance (t−1), while a second programmable logic control switch S₂ is electrically connected to the second storage element C₂ storing signal charges at a temporal instance (t). The temporal instances (t−1) and (t) may be successive temporal instances. Accordingly, the signal charges stored in the first storage element C₁ at the temporal instance (t−1) from the detector 115 _(i) is Q(t−1), shown in box 600 a. The signal charges stored in the second storage element C₂ at the second temporal instance (t) from the detector 115 _(i) is Q(t), shown in box 600 b. Each of the first storage element C₁, and the second storage element C₂ are electrically connected to a differential comparator circuit DA (e.g., through a MOSFET switch Q₁ and a MOSFET switch Q₂ respectively) to determine a trend 650 whether signal charges stored in the second storage element C₂ at a second temporal instance (t) is increasing or decreasing in comparison to signal charges stored in the first storage element C₁ at a first temporal instance (t−1), TREND(Q)=[Q(t)>Q(t−1)].

FIG. 7A depicts an example circuit module 700 (implementable as the circuit module 165 _(ai)) for determining a difference 750 of signal charges stored within the ROIC 160 at different temporal instances T_(i). FIG. 7B depicts a flow diagram representing a function of the example circuit module 700 of FIG. 7A. The example circuit module 700 includes two storage elements—a first storage element C₁ and a second storage element C₂ situated in parallel. A programmable logic control switch S is connected to the programmable logic control switches S₁ and S₂ for directing signal charges to the first storage element C₁ at a temporal instance (t−1) and the second storage element C₂ at a temporal instance (t) respectively. The temporal instances (t−1) and (t) may be successive temporal instances. The first storage element C₁ is electrically connected to programmable logic control switches S₁, S₄ at one end and S₃, S₅ at the other end. The programmable logic control switch S₃ electrically connects the first storage element C₁ to the second storage element C₂, which is also electrically connected through another programmable logic control switch S₂. Accordingly, the signal charges stored in the first storage element C₁ at the temporal instance (t−1) from the detector 115 _(i) is Q(t−1), shown in box 700 a. The signal charges stored in the second storage element C₂ at the second temporal instance (t) from the detector 115 _(i) is Q(t), shown in box 700 b. A difference 750 of the signal charges stored in the first storage element C₁ at the temporal instance (t−1) and the signal charges stored in the second storage element C₂ at the temporal instance (t) can be determined by first reversing the polarity of the first storage element C₁ and then electrically connecting the first storage element C₁ in parallel to the second storage element C₂. The reversal of polarity can be accomplished by ordered operations of the programmable logic control switches S₁, S₂, S₃, S₄ and S₅. For example, after the programmable logic control switches S, S₁ and S₅ are closed and the programmable logic control switches S₃ and S₄ are open, the signal charges flow into the first storage element C₁. Subsequently, the programmable logic control switches S₄ and S₃ are closed and the programmable logic control switches S₁ and S₅ are opened to reverse the polarity of the signal charges in the first storage element C₁ such that when the first storage element C₁ is electrically connected in parallel to the second storage element C₂, the difference 750 of the signal charges is thus DIFFERENCE(Q)=[Q(t)−Q(t−1)].

Though not shown in FIG. 7A, the difference 750 may be also determined by first reversing the polarity of second first storage element C₂ before electrically connecting the first storage element C₁ in parallel to the second storage element C₂. The reversal of polarity, in that case, can be accomplished by ordered operations of the programmable logic control switches S₁, S₂, S₃, S₄ and S₅ connected to the second storage element C₂ in a similar way as shown in FIG. 7A with respect to the first storage element C₁.

FIG. 8A depicts an example circuit module 800 (implementable as the circuit module 165 _(ai)) for determining a comparison 850 of signal charges stored within the ROIC 160 to a threshold value at any temporal instance T_(i). FIG. 8B depicts a flow diagram representing a function of the example circuit module 800 of FIG. 8A. The example circuit module 800 includes a storage element C electrically connected to an external reference voltage V_(ref) through a differential comparator circuit DA. The storage element C is electrically connected to a MOSFET switch Q₁ of the differential comparator circuit DA while the external reference voltage V_(ref) is electrically connected to a MOSFET switch Q₂ of the differential comparator circuit DA. This arrangement is used for illustrative purposes only and the circuit elements can be differently connected in different embodiments. Accordingly, the signal charges Q stored in the storage element C at any temporal instance T_(i) from the detector 115 _(i), shown in box 800 a, can be compared with a threshold value Q_(ref) corresponding to the external reference voltage V_(ref), to determine, in step 850, if the signal charges Q meets the threshold value Q_(ref), i.e. whether Q>Q_(ref). The example circuit module 800 in FIG. 8A can thus be used to determine whether the signal charges stored in an individual unit cell 165 _(i) or one or more subsets of individual unit cells 165 _(i) meets a threshold value by electrically connecting a storage element storing the signal charges and an external reference voltage V_(ref) corresponding to the threshold value through the differential comparator circuit DA.

A combination of one or more of the circuit modules 300, 400, 500, 600, 700, and 800 are implementable as the circuit modules 165 _(ai) within the individual unit cell 165 _(i). Moreover, the circuit topologies inherent in the circuit modules 300, 400, 500, 600, 700, and 800 are equally applicable for operating signal charges across any subset of adjacent unit cells within the ROIC 160. The circuit topologies inherent in the circuit modules 300, 400, 500, 600, 700, and 800 are also applicable across at least two subsets of adjacent unit cells 165 _(i). In some embodiments, the at least two subsets may form the entire plurality of unit cells 165 _(i) in the ROIC 160. In some embodiments, individual subsets of the at least two subsets of adjacent unit cells have an equal number of adjacent unit cells. In some embodiments, the individual subsets of the at least two subsets of adjacent unit cells have an equal number of adjacent unit cells and they together form the entire plurality of unit cells 165 _(i) in the ROIC 160. In all embodiments involving one or more subsets of adjacent unit cells, one or more additional programmable logic control switches may be coupled across the one or more subsets of adjacent unit cells within the ROIC 160 to achieve desired circuit topologies.

FIG. 9A depicts an example circuit module 900 for implementing a spatial shifting of signal charges stored across different unit cells 165 _(i) within the ROIC 160. FIG. 9B depicts a flow diagram representing a function of the example circuit module 900 of FIG. 9A. The example circuit module 900 includes a first storage element C₁ in a first unit cell 165 _(i(x-1)) and a second storage element C₂ in a second unit cell 165 _(ix) electrically connected through a programmable logic control switch S. The first unit cell 165 _(i(x-1)) and the second unit cell 165 _(ix) may be adjacent unit cells, or unit cells that are separated by other intervening unit cells. The programmable logic control switch S can be operated to direct signal charges from the first storage element C₁ to the second storage element C₂. Thus signal charges received by the first unit cell 165 _(i(x-1)) can be stored in the first storage element C₁ and subsequently copied into the second storage element C₂ in the second unit cell 165 _(ix). Accordingly, the signal charges stored in the first storage element C₁ in the first unit cell 165 _(i(x-1)) from the detector 115 _(i) is Q(x−1), shown in box 900 a. The signal charges directed into the second storage element C₂ in the second unit cell 165 _(ix) is Q(x), shown in box 900 b. The signal charges Q(x−1) and Q(x) can be then read out, one at a time, from the second unit cell 165 _(ix), to verify that Q(x−1)=Q(x).

FIG. 10A depicts an example circuit module 1000 for determining a summation of signal charges stored across different unit cells 165 _(i) within the ROIC 160. FIG. 10B depicts a flow diagram representing a function of the example circuit module 1000 of FIG. 10A. The example circuit module 1000 includes three storage elements situated in parallel—a first storage element C₁ in a first unit cell 165 _(i(x-2)), a second storage element C₂ in a second unit cell 165 _(i(x-1)) and a third storage element C₃ in a third unit cell 165 _(ix). It should be understood that the example circuit module 1000 is not limited to the embodiment shown in FIG. 10A and may contain more or fewer unit cells 165 _(i). The unit cells 165 _(i(x-2)), 165 _(i(x-1)) and 165 _(ix) may be adjacent unit cells, or unit cells that are separated by other intervening unit cells. The first storage element C₁ is electrically connected to the second storage element C₂ through a programmable logic control switch S₁₁. The second storage element C₂ is electrically connected to the third storage element C₃ through a programmable logic control switch S₂₁. Signal charges from detectors 115 _(ai), 115 _(bi) and 115 _(ci) are directed by the programmable logic control switches S₁, S₂ and S₃ to the first storage element C₁, the second storage element C₂ and the third storage element C₃ respectively. Accordingly, the signal charges stored in the first storage element C₁ is Q(x−2), shown in box 1000 a. The signal charges stored in the second storage element C₂ is Q(x−1), shown in box 1000 b. The signal charges stored in the third storage element C₃ is Q(x), shown in box 1000 c. When the first storage element C₁, the second storage element C₂ and the third storage element C₃ are electrically connected in parallel, the resultant voltage is the weighted average voltage representing the summation 1050 of the signal charges Q(x−2), Q(x−1), and Q(x), SUM(Q)=[Q(x−2)+Q(x−1)+Q(x)].

FIG. 11A depicts an example circuit module 1100 for determining a maximum value 1150 of signal charges stored across different unit cells within the ROIC 160. FIG. 11B depicts a flow diagram representing a function of the example circuit module 1100 of FIG. 11A. The example circuit module 1100 includes three storage elements situated in parallel—a first storage element C₁ in a first unit cell 165 _(i(x-2)), a second storage element C₂ in a second unit cell 165 _(i(x-1)) and a third storage element C₃ in a third unit cell 165 _(ix). It should be understood that the example circuit module 1100 is not limited to the embodiment shown in FIG. 11A and may contain more or fewer unit cells 165 _(i). The unit cells 165 _(i(x-2)), 165 _(i(x-1)) and 165 _(ix) may be adjacent unit cells, or unit cells that are separated by other intervening unit cells. A first programmable logic control switch S₁ is switchably connected to the first storage element C₁. The voltage developed across C₁ due to signal charges is applied to a metal-oxide-semiconductor-field-effect-transistor (MOSFET) Q₁, which is configured as a source-follower amplifier in conjunction with the output bias current generator BCG. It should be understood that other switching devices may be utilized instead. A second programmable logic control switch S₂ is switchably connected to the second storage element C₂ and the voltage is applied to MOSFET amplifier Q₂. A third programmable logic control switch S₃ is switchably connected to the third storage element C₃ and the voltage is applied to MOSFET amplifier Q₃. Signal charges from detectors 115 _(ai), 115 _(bi) and 115 _(ci) are directed by the programmable logic control switches S₁, S₂ and S₃ to the first storage element C₁ in the first unit cell 165 _(i(x-2)), the second storage element C₂ in the second unit cell 165 _(i(x-1)) and the third storage element C₃ in the third unit cell 165 _(ix) respectively. Accordingly, the signal charges stored in the first storage element C₁ is Q(x−2), shown in box 1100 a. The signal charges stored in the second storage element C₂ is Q(x−1), shown in box 1100 b. The signal charges stored in the third storage element C₃ is Q(x), shown in box 1100 c. Each output of source-follower amplifiers Q₁, Q₂ and Q₃ is applied to a common bias current connection through the bias current generator BCG so that only the amplifier with the largest input voltage will conduct current and thereby indicate the output voltage, which represents the maximum value 1150 of the signal charges stored in the storage elements C₁, C₂ and C₃, MAX(Q)=maximum value {Q(x−2), Q(x−1), Q(x)}.

FIG. 12A depicts an example circuit module 1200 for determining an increasing or decreasing trend 1250 of signal charges stored across different unit cells within the ROIC 160. FIG. 12B depicts a flow diagram representing a function of the example circuit module 1200 of FIG. 12A. The example circuit module 1200 includes two storage elements situated in parallel—a first storage element C₁ in a first unit cell 165 _(i(x-1)) and a second storage element C₂ in a second unit cell 165 _(ix). The unit cells 165 _(i(x-1)) and 165 _(ix) may be adjacent unit cells, or unit cells that are separated by other intervening unit cells. A first programmable logic control switch S₁ is electrically connected to the first storage element C₁, while a second programmable logic control switch S₂ is electrically connected to the second storage element C₂. Signal charges from detectors 115 _(ai) and 115 _(bi) are directed by the programmable logic control switches S₁ and S₂ to the first storage element C₁ in the first unit cell 165 _(i(x-1)) and the second storage element C₂ in the second unit cell 165 _(ix) respectively. Accordingly, the signal charges stored in the first storage element C₁ is Q(x−1), shown in box 1200 a. The signal charges stored in the second storage element C₂ is Q(x), shown in box 1200 b. Each of the first storage element C₁ and the second storage element C₂ are electrically connected to a differential comparator circuit DA (e.g. through a MOSFET switch Q₁ and a MOSFET switch Q₂ respectively) to determine a trend 1250 whether signal charges stored in the second storage element C₂ is increasing or decreasing in comparison to signal charges stored in the first storage element C₁, TREND(Q)=[Q(x)>Q(x−1)].

FIG. 13A depicts a first example circuit module 1300A and FIG. 13B depicts a second example circuit module 1300B for determining a difference 1350 of signal charges stored across different unit cells within the ROIC 160. FIG. 13C depicts a flow diagram representing a function of the example circuit modules 1300A, 1300B of FIGS. 13A-13B. The example circuit module 1300A includes two storage elements situated in parallel—a first storage element C₁ in a first unit cell 165 _(i(x-1)) and a second storage element C₂ in a second unit cell 165 _(ix). The unit cells 165 _(i(x-1)) and 165 _(ix) may be adjacent unit cells, or unit cells that are separated by other intervening unit cells. The first storage element C₁ is electrically connected to programmable logic control switches S₁, S₄ at one end and S₃, S₅ at the other end. The programmable logic control switch S₃ electrically connects the first storage element C₁ to the second storage element C₂, which is also electrically connected through another programmable logic control switch S₂. Signal charges from detectors 115 _(ai) and 115 _(bi) are directed by the programmable logic control switches S₁ and S₂ to the first storage element C₁ and the second storage element C₂ respectively. Accordingly, the signal charges stored in the first storage element C₁ is Q(x−1), shown in box 1300 a. The signal charges stored in the second storage element C₂ is Q(x), shown in box 1300 b. A difference 1350 of the signal charges stored in the first storage element C₁ and in the second storage element can be determined by first reversing the polarity of the first storage element C₁ and then electrically connecting the first storage element C₁ in parallel to the second storage element C₂. The reversal of polarity can be accomplished by ordered operations of the programmable logic control switches S₁, S₂, S₃, S₄ and S₅. For example, after the programmable logic control switches S₁ and S₅ are closed and the programmable logic control switches S₃ and S₄ are open, the signal charges flow into the first storage element C₁. Subsequently, the programmable logic control switches S₄ and S₃ are closed and the programmable logic control switches S₁ and S₅ are opened to reverse the polarity of the signal charges in the first storage element C₁ such that when the first storage element C₁ is electrically connected in parallel to the second storage element C₂, the difference 1350 of the signal charges is thus DIFFERENCE(Q)=[Q(x)−Q(x−1)].

Alternatively, the example circuit module 1300B (shown in FIG. 13B) may be used for determining a difference 1350 of signal charges stored across different unit cells within the ROIC 160. The example circuit module 1300B includes a current mirror circuit CMC electrically connected to the first unit cell 165 _(i(x-1)) and a storage element C in a second unit cell 165 _(ix). The unit cells 165 _(i(x-1)) and 165 _(ix) may be adjacent unit cells, or unit cells that are separated by other intervening unit cells. Signal charges from the detector 115 _(ai) are directed by the programmable logic control switch S₁ to the input of the current mirror circuit CMC for replicating a negative value of a flow of signal charges, I₁, through the first unit cell 165 _(i(x-1)). This negative replica, −I₁, of the flow of signal charges in the first unit cell 165 _(i(x-1)) is then directed to the storage element C in the second unit cell 165 _(ix). Simultaneously a flow of signal charges, I₂, from the detector 115 _(bi) are also directed by the programmable logic control switch S₂ to the storage element C in the second unit cell 165 _(i(x-1)). Accordingly, the difference 1350 of the signal charges from detectors 115 _(ai) and 115 _(bi) is stored in the storage element C and can be thus determined as DIFFERENCE(Q)=C*V(x)=∫(I₂−I₁)dt.

As a matter of general principle, the embodiments described herein and their combinations can be utilized to effectively control the flow of signal charges within one or more individual unit cells 165 _(i) comprising the ROIC 160. The programmable logic control switches in one or more individual unit cells 165 _(i) can be operably configured such that when a first storage element C₁ in a first unit cell 165 _(a1) stores a first set of signal charges received at a first temporal instance T₁, at least one second storage element C₂ in the first unit cell 165 _(a1) or a second unit cell 165 _(a2) stores a second set of signal charges received at at least one second temporal instance T₂.

The programmable logic control switches in one or more individual unit cells 165 _(i) can be operably configured to determine a summation of signal charges stored in the one or more individual unit cells 165 _(i) over a plurality of temporal instances T_(i) by electrically connecting in parallel the first storage element C₁ in the first unit cell 165 _(a1) and the at least one second storage element C₂ in the first unit cell 165 _(a1) or the second unit cell 165 _(a2).

The programmable logic control switches in one or more individual unit cells 165 _(i) can be operably configured to determine a difference of signal charges stored within the one or more individual unit cells 165 _(i) by reversing a polarity of the first storage element C₁ or the at least one second storage element C₂ after the first storage element C₁ stores the first set of signal charges received at the first temporal instance T₁ and the at least one second storage element C₂ stores the second set of signal charges at the second temporal instance T₂ but before the first storage element C₁ is electrically connected in parallel with the at least one second storage element C₂.

The programmable logic control switches in one or more individual unit cells 165 _(i) can be operably configured to determine a maximum value of signal charges stored over the plurality of temporal instances T_(i) by electrically connecting the first storage element C₁ to a first source-follower amplifier and the at least one second storage element C₂ to a second source-follower amplifier through a common bias current connection.

The programmable logic control switches in one or more individual unit cells 165 _(i) can be operably configured to determine whether the second set of signal charges stored in the at least one second storage element C₂ is increasing or decreasing in comparison to the first set of signal charges stored in the first storage element C₁ by electrically connecting the first storage element C₁ and the at least one second storage element C₂ to a differential comparator circuit.

Accordingly, in some embodiments, subsets of 2×2 unit cells 165 _(i) can be designed with programmable logic control switches and storage elements shared by all four unit cells 165 _(i), enabling that subset of 2×2 unit cells 165 _(i) to be further programmed for mathematical operations. The signal charges received by all four unit cells 165 _(i) at the same temporal instance T_(i) can be added as a sum to boost noise performance. The signal charges received by any one unit cell 165 _(i) can be subtracted from those received at the same temporal instance T_(i) by one or more unit cells 165 _(i) in the subset to improve unresolved target detection.

In some embodiments, one or more programmable logic control switches are configured to achieve time-delay-integration (TDI), especially for motion-related signal-starving applications. The one or more programmable logic control switches are coupled across one or more subsets of adjacent unit cells 165 _(i) by electrically connecting in parallel one or more storage elements C_(x) across the one or more subsets of adjacent unit cells 165 _(i) at successive temporal instances T_(i). Thus, the signal charges received in a first storage element C₁ in a first unit cell 165 ₁ at a first temporal instance T₁ are added to the signal charges received in a second storage element C₂ in a second unit cell 165 ₂, adjacent to the first unit cell 165 ₁, at a second temporal instance T₂, and so on. It is further contemplated that with real-time reprogramming based on properly coordinated metadata from external sources, TDI can be done efficiently in and around localized areas of the images of a moving target without the need to extend to the entire field-of-view (FOV) of the detector array 110.

Additionally, it is contemplated that in some embodiments, the detector array 110 may be coupled to a diffractive-filter array. In such embodiments, the one or more programmable logic control switches in the individual unit cell 165 _(i) can be additionally programmed to form spectral combs to identify and extract spectral signature information of an individual photon corresponding to an individual signal charge stored in the one or more storage elements C_(x) of the individual unit cell 165 _(i). Accordingly, the ROIC 160 is configured to extract multi-signature (spectral, temporal and spatial) data.

The embodiments described herein can be advantageously used for the design and operation of multi-function ROICs that enable programmable controls of how information from infrared radiation is received, stored, and conveniently extracted for subsequent production of infrared images. Many application-driven matrix operations can be achieved by first designing a selected set of storage elements in the ROIC coupled to another selected set of corresponding programmable logic control switches and then programming the set of programmable logic control switches to execute a sequence of operations over a period of time, to extract information-enriched data at or near the point of incidence of the infrared radiation. The extraction of information-enriched data and the subsequent processing through mathematical operations in the analog domain within the ROIC offers significant benefits, as compared to processing the data further downstream in the digital domain after passing through an analog-to-digital converter and a digital image processor. The produced images enjoy the least latency, minimal noise, and contain maximal information while consuming the least amount of bandwidth and energy. Accordingly, such ROICs can have useful applications requiring real-time information extraction in a multifunction sensor with limited bandwidth, such as the ones used or envisioned to be used in advanced threat warning, infrared search and track, and pilotage in degraded visual environment.

It is noted that the terms “substantially” and “about” may be utilized herein to include the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. These terms are also utilized herein to represent the degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function and intended scope of the subject matter at issue.

While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter. 

What is claimed is:
 1. A readout integrated circuit (ROIC) coupled to a detector array having a plurality of detectors for collecting photoelectrons over a plurality of temporal instances, the ROIC comprising a plurality of unit cells arranged in two spatial dimensions, wherein an individual unit cell of the plurality of unit cells is electrically coupled to an individual detector of the plurality of detectors to have one-to-one correspondence and comprises: one or more storage elements for storing signal charges representing the photoelectrons collected by the detector array at an individual temporal instance of the plurality of temporal instances; and one or more programmable logic control switches coupled to the one or more storage elements for directing the signal charges towards or away from the one or more storage elements at the individual temporal instance, wherein: a configuration of signal charges in the plurality of unit cells is mathematically represented and operated as a matrix in three dimensions having a plurality of elements; the three dimensions correspond to the two spatial dimensions and the individual temporal instance; and an individual element of the matrix has a value corresponding to the number of signal charges stored in the individual unit cell at the individual temporal instance.
 2. The ROIC of claim 1, wherein the storage element is a capacitor.
 3. The ROIC of claim 1, wherein: when the one or more programmable logic control switches form a closed switch, the signal charges are directed, at the individual temporal instance, towards the one or more storage elements in series with the one or more programmable logic control switches.
 4. The ROIC of claim 1, wherein the one or more programmable logic control switches in one or more individual unit cells are operably configured such that when a first storage element in a first unit cell stores a first set of signal charges received at a first temporal instance, at least one second storage element in the first unit cell or a second unit cell stores a second set of signal charges received at at least one second temporal instance.
 5. The ROIC of claim 4, wherein the one or more programmable logic control switches in the one or more individual unit cells are operably configured to determine a summation of signal charges stored in the one or more individual unit cells over the plurality of temporal instances by electrically connecting in parallel the first storage element and the at least one second storage element.
 6. The ROIC of claim 4, wherein the one or more programmable logic control switches in the one or more individual unit cells are operably configured to determine a difference of signal charges stored within the one or more individual unit cells by reversing a polarity of the first storage element or the at least one second storage element after the first storage element stores the first set of signal charges received at the first temporal instance and the at least one second storage element stores the second set of signal charges at the second temporal instance but before the first storage element is electrically connected in parallel with the at least one second storage element.
 7. The ROIC of claim 4, wherein the one or more programmable logic control switches in the one or more individual unit cells are operably configured to determine a maximum value of signal charge stored over the plurality of temporal instances by electrically connecting the first storage element to a first source-follower amplifier and the at least one second storage element to a second source-follower amplifier through a common bias current connection.
 8. The ROIC of claim 4, wherein: the one or more programmable logic control switches in the one or more individual unit cells are operably configured to determine whether the second set of signal charges stored in the at least one second storage element is increasing or decreasing in comparison to the first set of signal charges stored in the first storage element by electrically connecting the first storage element and the at least one second storage element to a differential comparator circuit.
 9. The ROIC of claim 4, wherein: the one or more programmable logic control switches in the one or more individual unit cells are operably configured to direct the first set of signal charges received at the first temporal instance in the first storage element to the second storage element during the at least one second temporal instance.
 10. The ROIC of claim 4, wherein: the at least one second storage element comprises a second storage element, a third storage element and at least one fourth storage element; the at least one second temporal instance comprises a second temporal instance and at least one third temporal instance; the first storage element stores the first set of signal charges received at the first temporal instance during the second temporal instance; the second storage element stores the second set of signal charges received at the second temporal instance; the third storage element stores a third set of signal charges received at the at least one third temporal instance; the one or more programmable logic control switches in the one or more individual unit cells are operably configured to hold a fourth set of signal charges in the first storage element, the second storage element or the at least one fourth storage element during the at least one third temporal instance while the third set of signal charges received during the at least one third temporal instance are stored in the third storage element; the fourth set of signal charges is formed by a mathematical operation of the first set of signal charges received at the first temporal instance and the second set of signal charges received at the second temporal instance; and the mathematical operation is selected from at least one of: a summation of signal charges, a maximum value of signal charges, trend determination of signal charges or a difference of signal charges.
 11. The ROIC of claim 1, wherein the one or more programmable logic control switches in the individual unit cell are operably configured to determine a summation of signal charges stored in the individual unit cell over successive temporal instances by electrically connecting in parallel individual storage elements of the one or more storage elements at the successive temporal instances.
 12. The ROIC of claim 1, wherein the one or more programmable logic control switches in the individual unit cell are operably configured to determine a maximum value of signal charges stored over successive temporal instances by electrically connecting the individual storage elements to a source-follower amplifier through a common bias current connection.
 13. The ROIC of claim 1, wherein: the one or more programmable logic control switches in the individual unit cell are operably configured to determine whether a signal charge stored in a second storage element at a second temporal instance is increasing or decreasing in comparison to a signal charge stored in a first storage element at a first temporal instance by electrically connecting the one or more storage elements to a differential comparator circuit; and the first temporal instance and the second temporal instance are successive temporal instances.
 14. The ROIC of claim 1, wherein the one or more programmable logic control switches in the individual unit cell are operably configured to determine a difference of signal charges stored within the individual unit cell over any two successive temporal instances by reversing a polarity of a first storage element or a second storage element after the first storage element and the second storage element store the signal charges at the two successive temporal instances but before the first storage element is electrically connected in parallel to the second storage element.
 15. The ROIC of claim 1, wherein the one or more programmable logic control switches in the individual unit cell are operably configured to determine whether a signal charge stored in an individual storage element of the one or more storage elements at the individual temporal instance meets a threshold value by electrically connecting the individual storage element and an external voltage corresponding to the threshold value through a differential comparator circuit.
 16. The ROIC of claim 1, wherein: the detector array is coupled to a diffractive-filter array; and one or more programmable logic control switches in the individual unit cell is further configured to identify and extract spectral signature information of an individual photon corresponding to an individual signal charge stored in the one or more storage elements.
 17. The ROIC of claim 1, further comprising: one or more programmable logic control switches coupled across a subset of adjacent unit cells within the ROIC.
 18. The ROIC of claim 17, wherein the one or more programmable logic control switches coupled across the subset of adjacent unit cells are operably configured to determine whether a signal charge stored in an individual unit cell in the subset of adjacent unit cells meets a threshold value by electrically connecting the one or more storage elements in the individual unit cell and an external voltage corresponding to the threshold value through a differential comparator circuit.
 19. The ROIC of claim 17, wherein: the one or more programmable logic control switches coupled across the subset of adjacent unit cells are operably configured to direct a first set of signal charges stored in a first storage element in a first unit cell to at least a second storage element in a second unit cell; and the first unit cell and the second unit cell are adjacent unit cells in the subset of adjacent unit cells.
 20. The ROIC of claim 17, wherein the one or more programmable logic control switches coupled across the subset of adjacent unit cells are operably configured to determine a summation of signal charges stored in the subset of adjacent unit cells by electrically connecting in parallel individual storage elements of the one or more storage elements across the subset of adjacent unit cells.
 21. The ROIC of claim 17, wherein the one or more programmable logic control switches coupled across the subset of adjacent unit cells are operably configured to determine a maximum value of signal charges stored in the subset of adjacent unit cells by electrically connecting individual storage elements of the one or more storage elements across the subset of adjacent unit cells to a source-follower amplifier through a common bias current connection.
 22. The ROIC of claim 17, wherein: the one or more programmable logic control switches coupled across the subset of adjacent unit cells are operably configured to determine whether signal charges stored in a second unit cell is increasing or decreasing in comparison to signal charges stored in a first unit cell by electrically connecting the one or more storage elements in the first unit cell and the second unit cell to a differential comparator circuit; and the first unit cell and the second unit cell are adjacent unit cells in the subset of adjacent unit cells.
 23. The ROIC of claim 17, wherein: the one or more programmable logic control switches coupled across the subset of adjacent unit cells are operably configured to determine a difference of signal charges stored in any two adjacent unit cells by reversing a polarity of a first set of storage elements in a first unit cell or a second set of storage elements in a second unit cell, after the first set of storage elements and the second set of storage elements store the signal charges but before the first set of storage elements is electrically connected in parallel to the second set of storage elements; and the first unit cell and the second unit cell are adjacent unit cells in the subset of adjacent unit cells.
 24. The ROIC of claim 17, wherein: the one or more programmable logic control switches coupled across the subset of adjacent unit cells are operably configured to determine a difference of signal charges stored in any two adjacent unit cells by directing a flow of signal charges in a first unit cell through a current mirror circuit and into a storage element in a second unit cell and directing a flow of signal charges in the second unit cell directly into the storage element; and the first unit cell and the second unit cell are adjacent unit cells in the subset of adjacent unit cells.
 25. The ROIC of claim 17, wherein the one or more programmable logic control switches coupled across the subset of adjacent unit cells are operably configured to achieve time-delay-integration (TDI) by electrically connecting in parallel the one or more storage elements across the subset of adjacent unit cells at successive temporal instances.
 26. The ROIC of claim 17, wherein: the one or more programmable logic control switches are coupled across at least two subsets of adjacent unit cells within the ROIC.
 27. The ROIC of claim 26, wherein individual subsets of the at least two subsets of adjacent unit cells together form the plurality of unit cells in the ROIC.
 28. The ROIC of claim 26, wherein individual subsets of the at least two subsets of adjacent unit cells have an equal number of adjacent unit cells.
 29. The ROIC of claim 28, wherein individual subsets of the at least two subsets of adjacent unit cells together form the plurality of unit cells in the ROIC.
 30. The ROIC of claim 26, wherein the one or more programmable logic control switches coupled across the at least two subsets of adjacent unit cells are operably configured to determine whether a signal charge stored in an individual unit cell in individual subsets of the at least two subsets of adjacent unit cells meets a threshold value by electrically connecting the one or more storage elements in the individual unit cell and an external voltage corresponding to the threshold value to a differential comparator circuit.
 31. The ROIC of claim 26, wherein: the one or more programmable logic control switches coupled across the at least two subsets of adjacent unit cells are operably configured to direct a first set of signal charges stored in a first storage element in a first unit cell to at least a second storage element in a second unit cell; and the first unit cell and the second unit cell belong to different subsets in the at least two subsets of adjacent unit cells.
 32. The ROIC of claim 26, wherein the one or more programmable logic control switches coupled across the at least two subsets of adjacent unit cells are operably configured to determine a summation of signal charges stored in the at least two subsets of adjacent unit cells by electrically connecting in parallel individual storage elements of the one or more storage elements across the at least two subsets of adjacent unit cells.
 33. The ROIC of claim 26, wherein the one or more programmable logic control switches coupled across the at least two subsets of adjacent unit cells are operably configured to determine a maximum value of signal charges stored in the at least two subsets of adjacent unit cells by electrically connecting individual storage elements of the one or more storage elements across the at least two subsets of adjacent unit cells to a source-follower amplifier through a common bias current connection.
 34. The ROIC of claim 26, wherein: the one or more programmable logic control switches coupled across the at least two subsets of adjacent unit cells are operably configured to determine whether signal charges stored in a second unit cell is increasing or decreasing in comparison to signal charges stored in a first unit cell by electrically connecting the one or more storage elements in the first unit cell and the second unit cell to a differential comparator circuit; and the first unit cell and the second unit cell belong to different subsets in the at least two subsets of adjacent unit cells.
 35. The ROIC of claim 26, wherein: the one or more programmable logic control switches coupled across the at least two subsets of adjacent unit cells are operably configured to determine a difference of signal charges stored in any two unit cells by reversing a polarity of a first set of one or more storage elements in a first unit cell or a second set of one or more storage elements in a second unit cell, after the first set of storage elements and the second set of storage elements store the signal charges but before the first set of storage elements is electrically connected in parallel to the second set of storage elements; and the first unit cell and the second unit cell belong to different subsets in the at least two subsets of adjacent unit cells.
 36. The ROIC of claim 26, wherein: the one or more programmable logic control switches coupled across the at least two subsets of adjacent unit cells are operably configured to determine a difference of signal charges stored in any two unit cells by directing a flow of signal charges in a first unit cell through a current mirror circuit and into a storage element in a second unit cell and directing a flow of signal charges in the second unit cell directly into the storage element; and the first unit cell and the second unit cell belong to different subsets in the at least two subsets of adjacent unit cells.
 37. The ROIC of claim 26, wherein the one or more programmable logic control switches coupled across the at least two subsets of adjacent unit cells are operably configured to achieve time-delay-integration (TDI) by electrically connecting in parallel the one or more storage elements across the at least two subsets of adjacent unit cells at successive temporal instances.
 38. An infrared sensor assembly comprising: a detector array having a plurality of detectors for collecting photoelectrons over a plurality of temporal instances; and a readout integrated circuit (ROIC) coupled to the detector array and comprising a plurality of unit cells arranged in two spatial dimensions, wherein: an individual unit cell of the plurality of unit cells is electrically coupled to an individual detector of the plurality of detectors to have one-to-one correspondence, and the individual unit cell comprises: one or more storage elements for storing signal charges representing the photoelectrons collected by the detector array at an individual temporal instance of the plurality of temporal instances; and one or more programmable logic control switches coupled to the one or more storage elements for directing the signal charges towards or away from the one or more storage elements at the individual temporal instance, wherein: a configuration of signal charges in the plurality of unit cells is mathematically represented and operated as a matrix in three dimensions having a plurality of elements; the three dimensions correspond to the two spatial dimensions and the individual temporal instance; and an individual element of the matrix has a value corresponding to the number of signal charges stored in the individual unit cell at the individual temporal instance. 